Harden the lua filter failure paths

1 file changed, 9 insertions, 5 deletions

diff --git a/source/filter.c b/source/filter.c
index f5f971c..a7efe56 100644
--- a/source/filter.c
+++ b/source/filter.c
@@ -173,6 +173,11 @@ static inline void unhook_write(void)
 
 static NORETURN void die_lua_error(struct lua_filter *filter)
 {
+	// The error page goes out through stdout, which may still be hooked
+	// to the very filter that failed, so the hook comes off first or the
+	// page would be fed back into the broken filter.
+	if (filter_write)
+		unhook_write();
 	die("Lua error in %s: %s", filter->script_file,
 	    lua_tostring(filter->lua_state, -1));
 }
@@ -336,11 +341,10 @@ static void cleanup_lua_filter(struct cgit_filter *base)
 {
 	struct lua_filter *filter = (struct lua_filter *)base;
 
-	if (!filter->lua_state)
-		return;
-
-	lua_close(filter->lua_state);
-	filter->lua_state = NULL;
+	if (filter->lua_state) {
+		lua_close(filter->lua_state);
+		filter->lua_state = NULL;
+	}
 	free(filter->script_file);
 	filter->script_file = NULL;
 }